Sasha CampbellThis article discusses causes of white spots on tomato leaves and other plant parts. Additionally, we will examine the damage they cause and explore natural remedies to help fix the problem.
Tomatoes are grown nearly everywhere in the world, in gardens and greenhouses.
Like any plant, they are vulnerable to various problems. These issues often appear as spots, patches, or specks on the fruit, stems, or leaves.
However, in some cases, the damage may be too severe for the plant to recover, especially if the underlying problem is not treated early.
Causes of White Spots on Your Tomato Plants (Plus How to Fix Naturally)
Below are some common causes of white discoloration on tomato leaves, fruits, stems, and other plant parts. We’ll also explore how to address the problem naturally.
1. Pest Activity
Stink bugs mainly damage tomato fruits, causing cloudy white or yellowish spots beneath the skin. Other pests, such as spider mites and thrips, may cause pale speckling or leaf discoloration.
Depending on the pest, both leaves and fruits may show signs of damage. You may also notice cloudy white spots beneath the fruit’s skin.
However, you can prevent or deal with stink bug infestations relatively easily.
Treatment:
- Handpicking
- Neem oil.
- Insecticidal soap.
- Strong spray of water.
Prevention:
- Weed control.
- Companion plants such as marigolds, basil, and nasturtiums.
2. Adverse Weather Conditions
Sunscald is caused by a plant getting too much sun and/or being in the path of hot, dry wind. Therefore, hot weather or extreme heat is the main culprit.
With this condition, unripe or ripening fruits begin to show pale white or yellowish blotches. However, sunscald can be prevented relatively easily.
Treatment:
- Removal of damaged fruit.
- Organic sun-protection products like IV Organic.
Prevention:
- Mulch
- Shade
- Water deeply in the morning to reduce heat stress.
- Avoid excessive pruning during hot weather.
3. Nutrient Deficiencies
The soil your tomato plant grows in plays a significant role in its health. While issues related to nutrients are not as common as the previous causes, they do occur.
Plants lacking certain nutrients may develop pale leaves, discoloration, or whitish spotting. Nutrient deficiencies most commonly linked to these symptoms include:
- Magnesium: May cause yellowing or pale areas between leaf veins.
- Iron: Often causes young leaves to become pale or yellowish-white.
- Manganese: Can lead to light spotting or interveinal chlorosis.
Applying compost, balanced organic fertilizers, or targeted foliar feeds may help correct deficiencies.
4. Disease
Diseases are another common cause of white spots on tomato plants.
High humidity, poor drainage, and low air circulation can lead to plant diseases. Lack of sun, cooler temperatures, and excessive watering can also be factors.
Septoria Leaf Spot
Septoria leaf spot first appears on the lower leaves of the plant. You may notice small circular gray or tan spots with dark borders.
As the disease progresses, the centers of the spots may become pale or whitish.
Treatment:
- Use organic fungicides.
- Remove or prune infected leaves.
Prevention:
- Crop rotation.
- Leaf debris disposal is necessary to keep the disease from overwintering.
Powdery Mildew
If your tomato leaves turn white, it is likely due to powdery mildew. This common disease appears as a thin, powdery layer on the leaves [1].
Treatment:
- Removing the dead leaves.
- Clearing plant debris.
- Vinegar.
- Neem oil.
- Baking soda spray.
- Liquid soap.
- Organic copper fungicides, such as Cueva, are effective.
Prevention:
- Watering early in the morning while avoiding wet foliage.
- Improving drainage.
- Providing access to plenty of sunlight.
Read more about how to get rid of powdery mildew on plants.
Leaf Mold
Tomato leaf mold mainly affects plants grown in greenhouses and in other enclosed spaces.
Symptoms may include faint green spots on the upper leaf surface. You may also notice small gray, yellow, or white specks.
It is caused by the fungus Passalora fulva [2]. In severe cases, it can also affect the blossoms and fruits.
Treatment:
- Prune where needed.
- Remove fallen leaves.
- Application of organic fungicides.
- Clean and disinfect greenhouse surfaces and tools at the end of the growing season.
Prevention:
- Improving air circulation.
- Lowering humidity to below 85%.
- Use drip irrigation to avoid overhead watering.
Sclerotinia Stem Rot (White Mold)
You will notice this around the time of flowering. White mold mainly affects plants in wet and cold climates.
Tomato stems will appear white, with black, pebble-like structures inside. Flowers may also have water-soaked areas.
Treatment:
- Remove all infected plants in severe cases.
- Prune leaves and lateral stems that are infected.
- Use a natural fungicide.
Prevention:
- Plant in containers with fresh soil.
- Keep tools and hands clean.
- Provide good drainage.
- Use drip irrigation to avoid overhead watering.
- Sterilize infected soil during the summer months by covering it with ground sheeting. This method allows the sun to raise the soil’s temperature, killing spores and mold.
Tomato Mosaic Virus (ToMV)
Tomato mosaic viruses can cause pale yellow, light green, or whitish mottled patterns on tomato leaves.
Spots on leaves may appear yellow-green or faintly white.
Treatment:
- Removal of all infected plants—they can’t be saved.
- Disinfect tools using rubbing alcohol or a bleach solution.
- Wash hands to prevent the spread of disease.
Prevention:
Disinfect tools regularly and avoid handling plants unnecessarily.
Recommendations
As soon as blemishes appear, action must be taken immediately, or the entire crop can be severely damaged. Therefore, pick any treatment or home remedy for white spots on tomato leaves from the list above.
Even removing damaged leaves early can help control the spread of disease. Moreover, prevention begins with how you set up your garden, the condition of the soil, and adequate drainage.
Proper transitioning from indoors to outdoors is also paramount if you start with seedlings.
See our complete list of tomato diseases (with pictures) and how to treat them naturally.
Takeaway
These are a few causes of white spots on your tomato plant’s leaves, stems, blossoms, and fruits. Some of them can be devastating to the crop. Tomato mosaic viruses can even spread to other susceptible plants.
However, despite the potential for issues, tomato plants also grow well alongside companion plants and are relatively easy to cultivate.
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